1. Field of the Invention
The field of the invention is ultrasonic probes, and particularly ultrasonic probes for catheter systems and provided in catheter tips for use with catheter systems.
2. Description of the Background Art
Ultrasound imaging of living human beings and animals has advanced in recent years in part due to advances in technologies related to computer data storage, transfer and analysis. Other advances, in the fields of component miniaturization and transducer design and composition, likewise have contributed to the advances in ultrasound imaging devices and methods.
Such advances have provided a foundation for development of various approaches to real time three dimensional (“RT3D”) ultrasonic imaging, including those that use a catheter-based ultrasound probe. Real time three dimensional ultrasonic imaging from a unit housed in a catheter offers many advantages for conducting exacting diagnostic and interventional procedures. Accordingly, improvements in this field are expected to offer substantial cost effectiveness and other benefits for medical diagnostics and interventions.
However, cost-effective delivery of accurate and reliable catheter-based ultrasonic probes remains a challenge. Several approaches to meet this challenge are known. U.S. Pat. No. 5,699,805, as one example, teaches an underfluid catheter system catheter-based imaging device having an ultrasound transducer array positioned longitudinally along the catheter. The ultrasound transducer array is connected to a drive shaft that rotates the array relative to the catheter body, to generate a plurality of spatially related two-dimensional tomographic images of body structure adjacent the catheter. A control system includes a drive mechanism that, as stated, may be positioned within the catheter body or, as shown in the disclosed embodiment, is remotely located from the catheter body. In the latter, disclosed embodiment, the drive shaft extends through the entire length of the catheter body.
U.S. Pat. No. 6,592,526 teaches a catheter that includes an integral catheter tip that comprises an array of at least one transducer for transmitting ultrasound energy radially outward, and for receiving ultrasound energy. In an illustrated embodiment, a plurality of transducers are placed circumferentially about the tip, and each transducer transmits and receives ultrasound energy. Between the transducers are a plurality of blind spots or blind areas. Imaging proceeds by rotation of the array, such as by using sets of actuators, such as nitinol actuators. Some actuators move the array in the circumferential direction, and some actuators move the array axially forward and back. Strain gauges provide information about positioning, and an acoustic transmission fluid fills an area about the array of transducers. It is stated that three-dimensional volumetric images may be obtained by use of this catheter tip.
These approaches, however, do not solve the problems of providing an acoustic transmission medium into a catheter tip in a desired manner and time, nor of effectively cooling the transducer array and internal actuator to stay within prescribed temperature limits during use within a living person. Nor do these approaches address the opportunity to mass produce ultrasonic probe catheter tips that may be later combined with a number of different types of catheters, thus providing for greater economies.
Thus, notwithstanding advances in the field, there remains a need for cost-effective approaches to providing catheter tips comprising an ultrasound transducer array that is movable from an internal actuator such as an electromechanical actuator, and that is suitable for use in ultrasonic imaging that may include real time three-dimensional imaging.